Lau and fellow believers regularly staged protests to explain the teachings of their spiritual movement and draw attention to the persecution of followers on the mainland, where the sect is banned. Until about a year ago, their protests were uneventful. That changed when a noisy rival group set up their placards and banners on the same pavement in the busy shopping area of Causeway Bay.

The 63-year-old Lau and her fellow protesters said they've been punched, shoved and sworn at since the newcomers from the "Care for the Youth Group Association Hong Kong" arrived with their blaring loudspeakers. Each protest is now a battle to be heard.

"It is much more difficult now given these attacks, this external pressure, these forces from China," said Lau amid the amplified din on Sogo Corner, Hong Kong's neon-lit version of New York's Times Square.

For critics of the pro-Beijing government in Hong Kong, groups like the Care for the Youth Group Association are part of a campaign from the mainland to tighten control over China's most freewheeling city. Increasingly, they say, Beijing is raising its voice. In the streets, boardrooms, newsrooms, churches and local government offices, individuals and organisations with links to the state and China's Communist Party are playing a bigger role in civil and political life, well-placed sources in Hong Kong and Beijing say.

Whenever there are anti-government public protests, a pro-Beijing counter movement invariably appears. This year's 25th anniversary commemoration of the protests centred on Beijing's Tiananmen Square drew a rival demonstration to defend China's bloody crackdown on June 4, 1989.

Mainland officials based in Hong Kong now routinely seek to influence local media coverage.

Catholic priests in Hong Kong report that agents from China's security service have stepped up their monitoring of prominent clergy.

And, Beijing's official representative body, the Liaison Office of the Central People's Government in Hong Kong, now is able to shape policy in the office of city chief executive Leung Chun-ying, say two sources close to the city's leader.

Residents of this global financial centre could not help noticing a more overt sign of China's rule in the former British colony: Huge Chinese characters spelling out "People's Liberation Army" in a blaze of neon alongside the military's waterfront headquarters that suddenly appeared at the beginning of June.

For Beijing's critics in Hong Kong, the 1997 handover is feeling more like a takeover. "Blatant interference is increasing," says Anson Chan, who led Hong Kong's 160,000-strong civil service in the last years of British rule and continued in that role for several years after the handover.

Chan cited as examples pressures on Hong Kong companies not to advertise in pro-democratic newspapers, attempts to limit debate about democratic reform, and the higher profile increasingly being taken by Beijing's official representatives in the city. "It's not another Chinese city and it shouldn't become one. Hong Kong is unique," said Chan.